1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a method and an apparatus for driving a liquid crystal display that perform signal processing on data having a linear characteristic and generate data signals having a linear characteristic to drive a liquid crystal display panel.
2. Discussion of the Related Art
In general, an active-matrix-type liquid crystal display (LCD) device has a switching device for selectively controlling light transmittance of liquid crystal cells in accordance with video signals to thereby display an image. The switching device for the active matrix LCD commonly uses a thin film transistor (TFT).
FIG. 1 is a schematic diagram of a driving apparatus for a liquid crystal display according to the related art. FIG. 2A is a graph representing a gamma value of an input data, and FIG. 2B is a graph representing a gamma value of the gamma voltage supplier according to the related art. In FIG. 1, a driving apparatus includes a liquid crystal display panel 2, a data driver 4, a gate driver 6, a gamma voltage supplier 8, a timing controller 10, and a signal processor 12. The crystal display panel 2 includes m data lines D1 . . . Dm and n gate lines G1 . . . Gn intersecting each other and defining m×n liquid crystal cells Clc arranged in a matrix. Thin film transistors TFT and storage capacitors Cst are formed in the liquid crystal cells Clc.
The signal processor 12 receives data from an input source (not shown) and performs signal processing on the data. In particular, the signal processor 12 receives data having a non-linear characteristic as shown in FIG. 2A. For example, TV signals generally are subject to a 2.2 gamma correction as shown in FIG. 2A such that they have a characteristic contrary to a cathode ray tube (CRT). Thus, the signal processor 12 receives such 2.2-gamma-corrected data having a non-linear characteristic and performs signal processing on the data. Then, the signal processor 12 applies the processed data to the timing controller.
The timing controller 10 re-arranges the processed data received from the signal processor 12, and applies the data to the data driver 4. In addition, the timing controller 10 receives a synchronizing signal from the input source (not shown) to generate a data control signal DCS and a gate control signal GCS for controlling the data driver 4 and the gate driver 6. Thus, the timing controller 10 also applies the data control signal DCS to the data driver 4, and the gate control signal GCS to the gate driver 6.
The data driver 4 then generates data signals using analog gamma voltages supplied from the gamma voltage supplier 8 and the data from the timing controller 10. In particular, the gamma voltage supplier 8 applies a plurality of analog gamma voltages having characteristics as shown in FIG. 2B, to linearly display 2.2 gamma-corrected data on the liquid crystal display panel 2. Thus, the data signals applied to the liquid crystal display panel 2 have a linear characteristic.
Further, the gate driver 6 sequentially applies a scanning pulse to the gate lines G1 . . . Gn in response to the gate control signal GCS to thereby select horizontal lines of the liquid crystal display panel 2 to display an image.
In the LCD according to the related art, the signal processor 12 changes 2.2 gamma-corrected data as shown in FIG. 2A to thereby improve display quality. However, there is a limit in making a signal processing using the gamma-treated data having a different input-to-output ratio. More specifically, when data is changed by the signal processor 12, data signals to be generated from the data driver 4 still need to have a linear characteristic. Thus, the signal processor 12 has to consider a characteristic of data signals to be generated later and a signal processing is thus limited. Therefore, the LCD according to the related art has a problem that some signal processing for improving a display quality cannot be made.